Algebra 1B?

Question

So far I have this

x-y=10
2x+3y=5

y=10+x

2x+30=15
-30 -30

2x=-15/2= -7

x=-7

Is that right? How do I solve for y?

This is the substitution method.

Please explain how you got the answer.

step by step directions

Answer 1

i dont think its right
x-y=10 > let this be our equation 1
2x+3y=5 > let this be our equation 2

From Eq 1

x=10+y this be Eq 3

Substitute Eq 3 into Eq 2
2(10+y) +3y=5
20+2y+3y=5
20+5y=5
5y=5-20
5y=-15
y=-3

put the value of y in eq 3
and we will have
x=10+y
x=10+(-3)
x=10-3
x=7

(7,-3) is the solution

Answer 2

It is not right.

if x -y = 10, then subtracting x from both sides gives
-y = 10 - x
Multiplying each side by -1 givs
y = -10 + x or y = x - 10
substituting into the second equation gives
2x + 3(x-10) = 5
or 2x + 3x -30 = 5
or 5x -30 = 5
or 5x=5 + 30
or 5x = 35
so x = 35/5 = 7

You are a minus sign off. Not bad.

Now that x = 7, substitute it into either equation
x - y = 10
7 - y = 10
y = x -10
y = 7 - 10 = -3

Answer 3

x-y=10
2x+3y=5

-y=10 - x
y = -10 + x

2x + 3( -10 + x) = 5
2x - 30 + 3x = 5
5x = 35
x = 7

Solve for y with the equation above: y = -10 + x
y = -10 + x = -10 + 7 = -3

(7,-3) is the solution

Answer 4

x - y =10
2x + 3y =5

x = y + 10
2 (y+10) + 3y = 5
2y + 20 + 3y = 5
5y = -15
y = -3

x = y + 10
x = -3 +10
x = 7

Hope this helps

Answer 5

Hold it right there, you messed up on something. -y=10-x, so
y=x-10, then you get 2x +3(x+10)=5. Multiply out and you get 5x=5-30, therefore x=-5. Plug it back in so you get (-5)-y=10
which means that -y=15, so y=15.

Answer 6

y = x - 10
2 x + 3 (x - 10) = 5
2x + 3x - 30 = 5
5x = 35
x = 7

y = 7 - 10
y = - 3

x = 7 , y = - 3

Answer 7

all of the previous answer are correct, however, i would like point out that the square root of eight can be simplified into 2 root 2... to do this you want to find a perfect square (4,9,16,25 ect.)as a factor of eight 4 and 2 are both factors of eight... so you can break down the square root of eight into the sqaure root of 4 times the square root of 2... as we know the square root of 4 is 2, therefore the simplified form of the square root of eight is 2 root 2

Answer 8

no the answer is wrong

x-10=y
2x+3(x-10)=5
2x+3x-30=5
5x-30=5
5x=35
x=7


then plug x=7 into x-y=10
so 7-y=10
-y=3
y=-3

hope that helps!!! :)

Answer 9

That is not correct its 7 just plug in 7 for x in either equation and then solve for y.

Answer 10

x-y = 10
fix to:
-y = 10 - x
y = -10 + x

then replace y with -10 + x
then when you know x, y = -10 + x